Battery cooling system

ABSTRACT

A cordless power tool has a housing which includes a mechanism to couple with a removable battery pack. The battery pack includes one or more battery cells as well as a vent system in the battery pack housing which enables fluid to move through the housing. A mechanism is associated with the battery pack to dissipate heat from the battery pack.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation-in-part of U.S. patentapplication Ser. No. 09/035,586, filed Mar. 5, 1998, now pending.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to battery cooling systems and,more specifically, to systems for cooling batteries for cordless powertools.

[0003] Cordless products which use rechargeable batteries are prevalentthroughout the workplace as well as in the home. From housewares topower tools, rechargeable batteries are used in numerous devices.Ordinarily, nickel-cadium or nickel metal-hydride battery cells are usedin these devices. Since the devices use a plurality of battery cells,the battery cells are ordinarily packaged as battery packs. Thesebattery packs couple with the cordless devices and secure to the device.The battery pack may be removed from the cordless device and charged ina battery charger or charged in the cordless device itself.

[0004] As the cordless power device is used, current flows through thebatteries to power the cordless device. As current is drawn off thebatteries, heat is generated within the battery pack. Also, duringcharging of the battery pack, heat is likewise accumulated during thecharging process. The heat created during discharge of the batteries aswell as charging of the batteries which, in turn, leads to increasedtemperatures, may have a severe effect on the life expectancy andperformance of the batteries. In order for batteries to properly charge,the batteries must be below a desired threshold temperature and thedifferential temperature between the cells in the battery pack should beminimized. Likewise, if the batteries become too hot during use, batterylife will be cut short. Also, if a battery is below a certain thresholdtemperature, it will be too cold to charge and must be warmed beforecharging. Thus, it is desirous to maintain batteries within a desiredtemperature range for optimum performance as well as optimum charging.

[0005] Further, battery packs typically contain some battery cells closeto the outer walls of the pack, while some battery cells are surroundedby other battery cells. Those cells close to the outer walls have betterthermal conductivity to the outside ambient than do the cells that aresurrounded by other cells. When a battery pack is discharging on thecordless device, the amount of heat generated is approximately the samein each cell. However, depending on the thermal path to ambient,different cells will reach different temperatures. Further, for the samereasons, different cells reach different temperatures during thecharging process. Accordingly, if one cell is at an increasedtemperature with respect to the other cells, its charge or dischargeefficiency will be different, and, therefore, it may charge or dischargefaster than the other cells. This will lead to a decline in theperformance of the entire pack.

SUMMARY OF THE INVENTION

[0006] The present invention provides the art with a battery pack whichdissipates heat within the battery pack during charging of the cells aswell as discharging of the cells while the battery pack is in use.

[0007] Additional objects and advantages of the invention will becomeapparent from the detailed description of the preferred embodiment, andthe appended claims and accompanying drawings, or may be learned bypractice of the invention

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings, which are incorporated in andconstitute a part of the specification, illustrate an embodiment of theinvention and together with the description serve to explain theprinciples of the invention. In the drawings, the same referencenumerals indicate the same parts.

[0009]FIG. 1 is a partial cross-section view of a cordless power tooland battery in accordance with the present invention.

[0010]FIG. 2 is a partial cross-section view of a battery pack inaccordance with the present invention.

[0011]FIG. 3 is a cross-section view of another embodiment of a batterypack in accordance with the present invention.

[0012]FIG. 4A is a cross-section view of another battery pack inaccordance with the present invention.

[0013]FIG. 4B is an elevation view of the battery pack of FIG. 4A.

[0014]FIG. 4C is a cross-section view of another battery pack inaccordance with the present invention.

[0015]FIG. 5 is another cross-section view of a battery pack inaccordance with the present invention.

[0016]FIG. 6 is an additional cross-section view of another embodimentof a battery pack in accordance with the present invention.

[0017]FIG. 7 is an additional cross-section view of a battery pack inaccordance with the present invention.

[0018]FIG. 8 is a cross-section view of an auxiliary fan module inaccordance with the present invention.

[0019]FIG. 9 is a perspective view of a charger in accordance with thepresent invention.

[0020]FIG. 10 is a cross-section view of the auxiliary fan modulecoupled with the charger of FIG. 9 in accordance with the presentinvention.

[0021]FIG. 11 is a cross-section view of another embodiment of thepresent invention of a charger of FIG. 9.

[0022]FIG. 12 is a cross-section view like that of FIG. 8 of anotherembodiment of an auxiliary fan in accordance with the present invention.

[0023]FIG. 13 is a perspective view of a battery cooler/heater inaccordance with the present invention.

[0024]FIG. 14 is a longitudinal cross-section view of FIG. 13.

[0025]FIG. 15 is a view like FIG. 14 of an additional embodiment of thebattery cooler/heater.

[0026]FIG. 16 is a top plan view of an additional embodiment of abattery pack in accordance with the present invention.

[0027]FIG. 17 is a front elevational view of the battery pack of FIG.16.

[0028]FIG. 18 is a partial cross-sectional view of the battery pack ofFIG. 16 along line A-A of FIG. 16 and another embodiment of the charger.

[0029]FIG. 19 is a partial cross-sectional view of the battery pack ofFIG. 16 along line A-A of FIG. 16 and another embodiment of the charger.

[0030]FIG. 20 is a front view of the battery pack plenum according tothe present invention.

[0031]FIG. 21 is a front view of the insulation plate according to thepresent invention.

[0032]FIG. 22 is an exploded perspective view of components of thebattery pack of FIG. 16.

[0033]FIG. 23 is a perspective view of the assembled components shown inFIG. 22.

[0034]FIG. 24 is a side elevational view of another battery packaccording to the present invention.

[0035]FIG. 25 is a side elevational view of the opening sealer of thebattery pack of FIG. 24.

[0036]FIG. 26 is side elevational view of the charger used with thebattery pack of FIG. 24.

[0037]FIG. 27 is a partial top plan cross-sectional view of the batterypack of FIG. 24 along line B-B of FIG. 27 and the charger of FIG. 27.

DETAILED DESCRIPTION

[0038] Turning to the figures, a cordless device is illustrated anddesignated with the reference numeral 20. The cordless device ordinarilyincludes a clamshell type housing 22. The housing 22 includes amechanism 24 to couple with a portion of a battery pack 26. The cordlessdevice 20 includes electrical elements 28 which couple with the batterypack electrical elements 29. Also, the device includes a trigger 30which energizes the motor 32 within the housing 22.

[0039] The battery pack 26 includes a housing 34 which contains aplurality of battery cells 36 within the housing 34. Also, the housing34 includes a ventilation system 38 which enables fluid to pass throughthe housing 34 and move around the cells 36 to dissipate heat from theplurality of cells 36 to the ambient air. The venting system 38ordinarily includes at least one inlet 40 and at least one outlet 42.The inlet and outlet are ordinarily apertures or slots in the housing34. Also, a channel 44 is formed within the housing 26 and aligned withthe inlet 40 to distribute the fluid flow around the battery cells 36 sothat all of the battery cells 36 are cooled. Preferably, the fluid flowscoaxially with respect to the axes of the batteries 36. Thus, as fluidenters into the channel 44, the fluid is directed over the battery cellsand does not pass over one cell to the next cell, etc., but is passedover a number of cells at one time so that the fluid passing through thehousing is not warmed by the first cell and then passed over the secondcell. However, fluid could be passed over the battery cells transverselywith respect to the battery cells axes.

[0040] Turning to FIG. 2, an additional embodiment of a battery pack isshown. The battery pack 26 is like that illustrated in FIG. 1, includingthe housing 34, ventilation system 38 with inlet 40 and outlet 42. Also,cells 36 are positioned within the housing. Additionally, the batterypack includes one or more baffles 46, 48, 50 and 52. The baffles directthe fluid to specific battery cells 36. Ordinarily, the fluid is passedinto channel 44 and distributed through the baffles 46 and 48.

[0041] Turning to FIG. 3, an additional embodiment of a battery pack isshown. Battery pack 60 includes a housing 62 with a venting system 64which enables fluid to pass around the battery cells 66. The ventilationsystem 64 includes at least one inlet 68 and at least one outlet 70.Also, the battery housing includes a fan 72. The fan 72 may include amotor 74 which may run off of the battery cells 36. Also, the fan motor74 may run off of a charging circuit when the battery pack is in acharger. The fan 72 moves fluid through the battery pack inlet. Thefluid is forced over the battery cells 66 and out the outlets 70. Thus,a positive pressure is created in the battery pack as fluid flowsthrough the battery pack 60. However, a negative pressure could becreated in the battery pack sucking fluid through the battery pack. Thechannels 73 direct the fluid through the battery cells so that the fluiddoes not continue to pass from cell to cell but passes over differentcells so that the cells experience the air at about the sametemperature.

[0042] Also, the battery housing may include baffles 75, 76, 77, 78 likethose described above.

[0043] Further, an auxiliary fan could be positioned in the tool housingitself as illustrated in phantom in FIG. 1 to move fluid through thebattery housing. Temperature sensors may be positioned in the housing tomonitor individual battery cell temperature. Also, the baffles may bedesigned to direct fluid flow to the hottest battery cells. Thus, thecells would be cooled as well as the temperature being equalized.

[0044] Turning to FIGS. 4A and 4B, an additional embodiment of thepresent invention is illustrated. Here, the battery pack includes ahousing 80, a plurality of cells 36 which are wrapped in a thermallyconductive but electrically insulating substance 83 to remove heat fromthe battery pack. Also, a heat sink 84 is positioned between the cellsfor wicking the heat from the battery cells 36. Projecting portions 86surround the batteries to effectively move heat towards the fins 88 ofthe heat sink 84. Also, a plurality of slots 90 are formed in thehousing 80 to enable the heat to be removed from the battery cells 36.The heat sink 84 may be any type of metallic sink with the projectingportion 82 either being metallic or a thermally conductive medium, suchas potting compound, gels or grease to extract the heat from the cellsto the heat sink 84. The heat exits through the fins 88. Also, morefins, as well as larger projecting portions, surround battery cellswhich are known to have higher temperatures during charging of thebattery as well as discharging when the tool is used. Thus, heat isdrawn from the battery cells 36 to the heat sink. The ventilation slots90 enable fluid to pass over the fins 88 to remove heat. Also, an inlet92 may be included in the housing to enable fluid to pass from a fan inthe tool housing through the battery pack.

[0045]FIG. 4C illustrates an additional embodiment of the presentinvention. The battery pack is similar to that in FIGS. 4A and 4B,except the housing 80′ does not include the plurality of slots. Theplurality of cells 36 are wrapped in a thermally conductive butelectrically insulating substance such as tape 83 to enable heat to movefrom battery to battery via a heat sink 84. The heat sink 84 ispositioned between the cells to wick heat from hotter battery cells andtransfer the heat to battery cells having a lower temperature so thatthe temperatures of the cells are equalized within the pack. Projectingportions 86 surround the battery cells to effectively remove heattowards the fins of the heat sink 84. Cells which are known to havehigher temperatures are designated with 36′. Further, the heat sink maybe a metallic type like that mentioned above, or may include thermallyconductive mediums such as potting compound, gels or grease to extractheat from hotter cells and move it to the heat sink which, in turn,distributes the heat to the remaining cells such that the temperaturewithin the cells is equalized. Thus, the temperature equalization of thecells enables the cells to be charged and discharged at a substantiallyequal rate which improves and increases the life of the battery pack.

[0046] Turning to FIG. 5, an additional embodiment is illustrated. InFIG. 5, the battery pack includes a housing 100 surrounding a pluralityof cells 36. The housing 100 includes a plurality of slots 102 which actas outlets and an inlet 104. Also, a heat pump 106 is positioned withinthe housing 100. The heat pump 100 is a Peltier device, which iscommonly known in the art. The Peltier device is coupled with heat sinks108 and 110. As the Peltier device is activated, one heat sink becomescold while the other becomes hot. If the current through the Peltierdevice is reversed, the cold and hot sides reverse. Thus, the heat sinks108, 110 can be used to provide cool air into the battery housing 100and enable the air to be baffled by baffles 112, 114, 116 and 118 topass over the battery cells 36 and exit the housing through the outletslots. Thus, cool air would be passed into the housing to cool thebatteries. In the event that the battery cells are cold, the Peltierdevice current could be reversed wherein heated fluid would be passedthrough the battery pack to warm the battery cells so that they could becharged. The Peltier device is coupled to electronics 120 which mayfunction off of the battery cells, a charger, or both, to control thecooling or heating. Also, a temperature sensor 122 may be positioned inthe housing, with respect to the battery cells, so that heating andcooling may take place as desired.

[0047]FIG. 6 is a view like that of FIG. 5 including the heat pump 106.Additionally, a fan 124 is positioned within the housing to move thefluid through the battery pack 100. Here, fluid can be channeledthroughout the battery enabling the battery to be cooled.

[0048] Turning to FIG. 7, a battery pack is illustrated and designatedwith the reference numeral 130. Here, the battery pack is similar tothat illustrated in FIG. 4, however, a fan 132 is positioned within thebattery pack. The fan 132 moves fluid across the fins 88 in an attemptto expel the heat from the battery pack housing 130.

[0049] Turning to FIG. 8, an auxiliary fan module is illustrated anddesignated the reference numeral 140. The auxiliary fan module 140includes a housing 142 which houses a fan 144. The housing includes aninlet 146 as well as an outlet 148. Fluid flows through the outlet 148,which is surrounded by seal 149, into the battery pack inlet 40 likethat illustrated in FIGS. 1, 2. Electrical contacts 150 are positionedwithin the housing 142 to couple with the battery electrical contacts 29to charge the battery cells 36. Further, electrical contacts 152 aresecured with the housing 142 to mate with electrical contacts in acharger to run the fan during charging of the battery cells. Further, anelectronic package 154 is within the housing 142 to control charging ofthe battery as well as operation of the fan 144. The electronic package154 may be coupled with the temperature sensor to operate the fan asneeded.

[0050] Turning to FIG. 9, a perspective view of a battery charger isillustrated and designated with the reference numeral 160. The charger160 includes contacts 162 to couple with a battery pack or auxiliary fanmodule to charge a battery pack. The charger 160 includes a base 164which includes the electrical contacts coupled with the base. Further avent system 166, with inlet 167 and outlet 169, is coupled with the base164 to enable air to pass into and through the battery charger and inturn the battery pack. Further, the battery charger includes anelectronics package 168 which receives the current from an AC source andconverts it into the DC source required to charge the battery pack.

[0051] The charger 160 may be utilized with the disclosed battery packswith or without fans in the battery pack. In the event a battery pack isused which does not include a fan, convection would be used to enableair flow through the vent system 160 and in turn through the batterypack. In a situation where the battery pack includes a fan, the contacts162 would also couple with the fan electronics within the battery packto for operating the fan. In this event, the electronics in the chargerwould electrically couple with the fan electronics to turn on and turnoff the fan when needed.

[0052] Also, the charger could be utilized with the auxiliary fan module140 as illustrated in FIG. 10. Here, the auxiliary fan module 140 iscoupled with the electrical contacts 162 in the charger 160 to operatethe fan 144 within the auxiliary fan module 140. Accordingly, the fan144 may be turned on and off as desired.

[0053] Turning to FIG. 11, a charger 180 is shown. The charger 180 issimilar to the battery charger 160 except that the battery charger 180includes a fan 182 coupled with the venting system 166. The fan 182moves fluid through an inlet 184 and forces the fluid through an outlet186 into the battery pack. In this type of charger 180, the fan 182would be activated as desired. Further, the charger electronics could becoupled with a sensor inside of the battery pack which would beactivated through the electrical contacts 162. The sensor would sensethe temperature within the battery pack so that the fan could runintermittently. Also, the sensors may be removed and the fan would justrun constantly while the charger is operating.

[0054] Turning to FIG. 12, an auxiliary fan module is illustrated likethat in FIG. 8. Here, the auxiliary fan module 190 includes a fan 192,an inlet 194 and an outlet 196 in the housing 198. Also, a heat pump 200as described above is positioned within the housing 198. The heat pumpwould produce a cold heat sink 202 which would enable fluid to move into the housing, via the fan, and pass over the cold heat sink and intothe battery pack. The fluid would also pass over the hot side of theheat sink 206, withdrawing heat from the housing, and exhausting the airto ambient through outlet 208. In the event the battery pack is cold,the heat pump 200 may be reversed and heat may be passed into thebattery pack to warm the battery pack before charging. The fan module190 also includes electrical contacts 210 to couple with the batterypack. Also, electrical contacts 212 couple with the charger 160. Theelectronics 214 within the auxiliary fan module 190 couple with thecharger and operate the fan to move fluid into the battery pack asdesired.

[0055] Turning to FIGS. 13-15, additional embodiments of the presentinvention are shown. FIG. 13 illustrates a perspective view of a batterycooler/heater device. Here, the battery cooler/heater 220 includes ahousing 222. The housing 222 includes a battery receiving portion 224.The battery receiving portion 224 may be a cutout or the like in thebattery housing 222 forming a depression to receive a battery housingpack. Further, the housing includes an inlet 226 and an outlet 228. Theinlet enables fluid to pass into a duct in the housing 222 while theoutlet enables the fluid to be passed out of the housing duct and into abattery pack. The inlet 226 is generally covered by a filter 230 and agrill 232 is attached to the housing 222 sandwiching the filter betweenthe inlet and the grill 232. The grill 232 has slots 234 to enable airto pass through the grill into the filter and turn through the inlet226.

[0056] An O-ring or some type of seal 236 is positioned around theoutlet 228 as shown in FIG. 14. The seal 236 mates with the battery packto prohibit fluid from escaping around the battery pack housing whilefluid is passed into the battery pack housing.

[0057] In FIG. 14, the housing 222 includes a fan 240 to move fluidbetween the inlet 226 and outlet 228. The fan 240 is energized andde-energized by a switch 242. In FIG. 14, the switch 242 is a manualswitch enabling the user to manually turn on and turn off the fan 240 asdesired. Also, a power cord 244 is coupled with the fan and switchelectronics 246 to provide power to the battery cooler/heater 220.

[0058] Additionally, a Peltier device 250 (illustrated in phantom) maybe positioned near the inlet which may provide cooled or heated fluidwhich is drawn into the battery pack as described above. The Peltierdevice 250 would be coupled with the electronics 246 so that the Peltierdevice 250 may deliver cold or hot fluid flow, depending upon if coolingor heating is desired, to the battery cells.

[0059] Turning to FIG. 15, an additional embodiment of the batteryheater/cooler 220 is shown. Here, the battery cooler is like thatdescribed above, except that an automatic switch 260 has replaced themanual switch 242. Here, as the battery pack housing is slid into thebattery cooler/heater housing, the battery contacts the normally openswitch 260 energizing the fan 240. As the battery pack housing iswithdrawn from the battery cooler/heater, the switch 260 would return toits normally open position, de-energizing the fan.

[0060] Referring to FIGS. 16-18, a battery pack 300 has a housing 310,at least one cell 318 enclosed in the housing 310 and terminals 311connected to the cell 318.

[0061] Preferably the housing 310 comprises two clamshell halves 310Cheld together by screws 310S. The housing 310 may also have an uppertower 310B where the terminals 311 are disposed. A cell 318 may bedisposed within the tower 310B. Exhaust holes 315 are preferablydisposed on the front wall 310F and/or rear wall 310R of the housing310.

[0062] Because battery pack 300 is inserted into a tool or charger bysliding the entire pack 300 along direction X, it is preferable toprovide protrusions 312 on the side walls of the housing 310. Preferablyprotrusions 312 extend from the side walls so as to provide the userwith a grasp on the housing 310 when removing the battery pack 300 fromthe tool or charger.

[0063] Persons skilled in the art will recognize that in the presentcase direction X is substantially parallel to the terminals 311 and/orthe longitudinal axis of battery pack 300. However, such persons shouldalso recognize the direction X may be at an angle off the terminals 311and/or the longitudinal axis of battery pack 300.

[0064] Preferably terminals 311 are disposed on duct assembly 320. Ductassembly 320 may have walls 313 disposed between terminals 311. Inaddition, duct assembly 320 may include a duct path 321. The ductassembly 320 may also have a duct grill 321G to prevent dust, chips orother things from entering duct path 321.

[0065] Duct path 321 may be connected to a hollow plenum 340. The plenum340 preferably has opposing walls 340R and 340F. Each wall may havebosses 344 contacting bosses 343 disposed on the other wall. Plenum 340may be built of one piece, or of multiple pieces assembled together.

[0066] Preferably cell 318 is disposed against plenum 340. Referring toFIGS. 18 and 20, it is preferable to dispose 10 cells on both sides ofplenum 340. Ribs 342 may hold each cell or a group of cells in place.Internal ribs 310RR may also hold each cell or a group of cells 318 inplace relative to plenum 340.

[0067] With such arrangement, air or fluid entering through duct path321 will flow into the plenum 340. The plenum 340 preferably has holesfor allowing the air or fluid to escape therefrom and to flow along thecells 318 towards the outlet holes 315 on housing 310.

[0068] It has been found that cells 318 closest to the center of thepack 300 tend to cool slower than those cells farthest from the centerof the pack 300. If the holes on the plenum 340 have the same diameter,all cells will receive the same air or fluid flow. However, by alteringthe size of holes, it is possible to control the air or fluid flow alongcells 318 and thus allow more air or fluid to flow along the cellsclosest to the center of the pack, than to the cells farthest from thecenter of the pack.

[0069] Accordingly, a plenum wall may be provided with the smallestholes 343 towards the periphery of the cell cluster, i.e., the group ofcells. Similarly, the plenum wall may be provided with the largest holes345 at or near the center of the cell cluster. The plenum wall may beprovided with mid-size holes 344 in between. Preferably the holes aredisposed between two or three cells 318.

[0070] In a battery pack 300 with cells 318 which have a diameter ofabout 22.5 mm, the diameters of holes 343, 344, and 345 would preferablybe about 6 mm, about 8 mm and about 12 mm, respectively. In other words,the diameters of holes 343, 344 and 345 would be about 0.267, about0.355, and about 0.533 times the diameter of cells 318, respectively.

[0071] At the end of the cells 318 farthest away from the plenum 340, itis preferable to provide an insulation plate 330, as shown in FIGS. 18and 21-23.

[0072] Preferably, the insulation plate 330 is made of a non-conductivematerial, and it may have an adhesive material disposed on both sides ofthe plate 330.

[0073] To assist in the cooling of the cells 318, the plate 330 alsohave holes disposed thereon. Preferably, these holes have differentdiameters.

[0074] Accordingly, the plate 330 may be provided with a center hole332. The plate 330 may be provided with holes 334 and 333. Holes 334 arefarther than holes 333 from center hole 332. Accordingly, it ispreferable to make holes 334 smaller than holes 333. Preferably theholes are disposed between two or three cells 318.

[0075] In a battery pack 300 with cells 318 which have a diameter ofabout 22.5 mm, center hole 332 is preferably about 12 mm wide and 25 mmlong. Also, the diameters of holes 333 and 334 would preferably be aboutabout 8 mm and about 10 mm, respectively. In other words, the diametersof holes 333, 334 would be about 0.355, and about 0.444 times thediameter of cells 318, respectively.

[0076] Filter 339 is preferably disposed on plate 330 to prevent dustfrom and/or limit the amount of dust entering the housing 310 throughholes 315. Preferably filter 339 is made of a synthetic fabric mesh.

[0077] Battery pack 300 may also have a temperature indicating device317 connected to terminals 311, to indicate the temperature of cells318. Such temperature indicating device 317 may be a thermistor, acapacitor, a thermostat, etc. The temperature indicating device 317 maybe provided between a cell 318 and the plenum 340 (see FIG. 19), or on acell 318 or between cells 318 (see FIG. 18).

[0078] If provided on a cell 318, the temperature indicating device 317may be taped onto cell 318. The temperature indicating device 317 may becovered so that it be not exposed to the air or fluid flow.Alternatively, the temperature indicating device 317 may be leftuncovered and exposed to the air or fluid flow.

[0079] Accordingly the battery pack 300 may be manufactured as follows:a person would take 10 cells 318 and form first and second clusters318A, 318B. Preferably, the person would wrap tape around the clusters318A, 318B to hold them together. Lead plates 316 are then connected tothe different cells 318.

[0080] The terminals leads 314, which are connected to terminals 311,are also connected to two cells 318. Depending on the preferredembodiment, a temperature indicating device 317 may be disposed betweencells 318, or attached to a cell 318 or to the plenum 340. Jumper leads316J are then connected to bridge two cells of both clusters 318A, 318B.(In this manner, both clusters will constitute a series of batterycells. Persons skilled in the art should recognize that other leadconnecting arrangements may be implemented if it is preferred to disposecells in parallel or series-parallel arrangements, etc.)

[0081] The first cluster 318A can then be disposed on one side of theplenum 340. Similarly, the second cluster 318B can be disposed on theother side of the plenum. Preferably the clusters 318A, 318B will engageplenum ribs 342.

[0082] Insulation plates 330 and filters 339 can then be disposed on theclusters 318A, 318B. The duct assembly 320 is then disposed on plenum340. The entire assembly is then disposed in the housing clamshells310C. Screws 310S are preferably used to attach both clamshells 310C.

[0083] Foam or rubber pads may be disposed on the different elements toensure a good fit with housing 310. For example, rubber pads 338 may bedisposed on the clusters 318A, 318B, etc.

[0084] Referring to FIG. 18, a charger 400 is used for charging batterypack 300. The charger 400 may have a fan 401 for moving air or fluidthrough battery pack 300. In other words, this fan 401 may blow or suckair or fluid through battery pack 300. For the sake of convenience, theembodiment disclosed herein will show air being blown from the chargerto and through the battery pack 300, but persons skilled in the art areadvised that other fluids may be moved therethrough, and/or that the airor fluid may flow from the battery pack 300 into the charger 400 or theatmosphere.

[0085] As shown in FIG. 18, fan 401 preferably moves air or fluidthrough battery pack 300 via a duct 406. Cool air may be brought inthrough inlet holes 402 disposed on the charger 400. Duct 406 connectswith duct 321. Preferably both ducts are flushed together so that no gapexists therebetween. Furthermore, both ducts may also be axiallyaligned.

[0086] Fan 401 may also have an outlet 407 for blowing air through thecharger 400, so as to cool the charger electronic components 403. Outletholes 404 are disposed on charger 400 so as to allow warmer air to exit.

[0087] Charger 400 may also have outlet holes or vents 405. Accordingly,air exiting from the battery pack 300 may form a low pressure regionabove vents 405, “pulling” air from the charger 400 outwardly. Thiswould promote air cooling of the charger electronic components 403.

[0088]FIG. 19 shows a similar charger 400′. In this charger, ducts 406and 321 are not flushed together. Instead, a chamber 406C is disposedtherebetween. Second, ducts 406 and 321 are not axially aligned.

[0089] It is known in the art to turn on the fan 401 when the batterypack 300 is inserted and to turn it off completely when the chargingprocess is completed or the battery pack 300 is removed. However, otherfan modulation processes are also useful.

[0090] First, it is preferable that fan 401 is turned on for apredetermined period and turned off before a battery pack 300 isdisposed on the charger. This period could occur when the charger 400 iseither turned on, connected to an outlet or when a button on the chargeris pushed. This would blow foreign particles, such as dust, that hassettled on duct 406 and/or chamber 406C. Accordingly, such particleswould not be blown into the battery pack 300 during charging. Thisresult can also be achieved if the fan 401 is always on, on after thebattery pack 300 has been removed, or if the fan 401 is periodicallyturned on and off when the battery pack 300 is not disposed in thecharger.

[0091] In addition, rather than fan 401 being completely turned off, itmay be expedient to just regulate the power sent to fan 401 so that fan401 rotates at a lower speed. Accordingly, fan 401 can rotate at a firstspeed before the battery pack 300 is disposed on the charger 400. Whenthe battery pack 300 is disposed on the charger 400, the fan 401 canrotate at a second speed, which is higher than the first speed. When thebattery pack 300 is then removed, the fan 401 can be turned offcompletely or brought back to a lower speed. This would also help inmaintaining the duct 406 dust-free.

[0092] Accordingly, it may be preferable to turn on fan 401 at a highfirst speed for a predetermined period and then lower the speed before abattery pack 300 is disposed on the charger. This period could occurwhen the charger 400 is either turned on, connected to an outlet or whena button on the charger is pushed.

[0093] Furthermore, the charger 400 can control the speed of fan 401 byusing information from the temperature indicating device 317. Forexample, the charger 400 would receive information from the temperatureindicating device 317. If the battery pack 300 is too cold, e.g., below20° C., the charger 400 would lower the speed or stop fan 401.Similarly, the charger can control fan 401 so as to maintain thetemperature of battery pack 300 around a predetermined point, such asabout 30° C.

[0094] In addition, charger 400 can control fan 401 so as to obtainaccurate information from the temperature indicating device 317. Forexample, in an embodiment discussed above, the temperature indicatingdevice 317 was exposed to the air or fluid flow. Accordingly, thetemperature indicating device 317 would show a cell temperature lowerthan the actual cell temperature. This is would render the differenttemperature-based charge termination processes useless.

[0095] Such result can be avoided if the charger 400 periodically lowersthe speed of or stops fan 401 for a predetermined period of time. Thiswould allow temperature indicating device 317 to show a more accuratecell temperature, which can then be read by the charger 400 and used inits temperature analysis. The charger 400 can then increase the speed ofor start fan 401 until the next time the charger 400 needs temperatureinformation.

[0096] Another battery pack and charger are shown in FIGS. 24-27. Theteachings of the above embodiments are incorporated herein. In thepresent embodiment, battery pack 500 has a housing 501. Housing 501contains cells 502 disposed horizontally and/or substantiallyperpendicular to the direction of insertion, i.e., direction Y, and/orto the longitudinal axis of battery pack 500.

[0097] Housing 501 has holes 503 on one side. A slidable door 510 isdisposed near holes 503 for sealing them. Door 510 may be disposedinside or outside housing 501. Housing 501 may have rails 511 slidablyreceiving door 510. Door 510 may have alternating slats 510S and holes510H. Accordingly, when door 510 is in an open position, holes 510Halign with holes 503, allowing air or fluid to enter battery pack 500.When door 510 is in a closed position, slats 510S align andsubstantially close or seal holes 503. Preferably, springs 512 connectedto housing 501 bias door 510 towards the closed position.

[0098] When battery pack 500 is disposed on a charger 600 for charging,the battery pack 500 is moved along the direction of insertion, causingprotrusion 602 to contact door 510 and/or door protrusion 510B. This inturn would cause door 510 to move towards the open position.

[0099] When in the open position, air blown by fans 601 will enterthrough holes 503, go through holes 510H, flow along cells 502, and exitthrough holes 504 disposed on the housing 501. Persons skilled in theart will recognize that the cells 502 may be disposed on a plate 517 andheld in place by plate ribs 517 or housing ribs 501R. As before, it ispreferable to provide an insulation plate 515 and a filter 516.

[0100] In addition, persons skilled in the art should recognize thatfans 601 can also suck air, so that the air enters and exits the batterypack 500 through holes 504 and 503, respectively.

[0101] While the above detailed description describes the preferredembodiment of the present invention, the invention is susceptible tomodification, variation, and alteration without deviating from the scopeand fair meaning of the subjoined claims.

1. A battery pack to be inserted in an electrical appliance by movementalong a first direction comprising: a housing having top, bottom andside walls, a terminal tower disposed on the top wall, an air inletdisposed on at least one of the terminal tower and the top wall, and anair outlet for allowing air to exit from the housing; a plenum disposedwithin the housing and connected to the air inlet, the plenum having atleast one hole for allowing air to move therethrough; a first celldisposed within the housing and against the plenum; a filter disposedwithin the housing and near the air outlet; and an insulation platedisposed between the filter and the first cell.
 2. The battery pack ofclaim 1, wherein the air outlet is disposed on one of the side walls. 3.The battery pack of claim 1, wherein the first cell has a longitudinalaxis substantially parallel to the first direction.
 4. The battery packof claim 1, wherein air entering the housing through the air inlet movesalong a second direction substantially perpendicular to the firstdirection.
 5. The battery pack of claim 1, wherein air exiting housingthrough the air outlet moves along a second direction substantiallyparallel to the first direction.
 6. The battery pack of claim 1, whereinthe plenum comprises at least one rib for holding the first cell inplace.
 7. The battery pack of claim 1, wherein the housing comprises atleast one rib for holding the first cell in place.
 8. The battery packof claim 1, further comprising a temperature indicating device.
 9. Thebattery pack of claim 8, wherein the temperature indicating device isexposed to the air entering and exiting the housing.
 10. The batterypack of 8, wherein the temperature indicating device is one of the groupconsisting of thermistors, thermostats, capacitors and resistors. 11.The battery pack of claim 1, further comprising a second cell disposedwithin the terminal tower.
 12. The battery pack of claim 1, furthercomprising a set of cells surrounding the first cell.
 13. The batterypack of claim 12, wherein the plenum has first and second sets of holes,where the first set of holes is closer to the first cell and the secondset of holes is farther from the first cell and closer to the set ofcells surrounding the first cell.
 14. The battery pack of claim 13,wherein diameter of the holes in the first set is larger than diameterof the holes in the second set.
 15. The battery pack of claim 1, havinga movable door disposed on the housing, the door being movable between afirst position closing the air inlet and a second position opening theair inlet.
 16. The battery pack of claim 15, wherein the door slidesbetween the first and second positions.
 17. The battery pack of claim15, wherein the door moves between the first and second position whenthe battery pack is disposed on a charger.
 18. The battery pack of claim15, further comprising a spring biasing the door towards the firstposition.
 19. A method for manufacturing a battery pack, comprising:providing a first plurality of cells; assembling the first plurality ofcells into a first cluster; disposing the first cluster on a plenum;disposing a first insulation plate on the first cluster; disposing afirst filter on the first insulation plate; and disposing the firstcluster and plenum within a housing.
 20. The method of claim 19, furthercomprising disposing a temperature indicating device within the housing.21. The method of claim 19, further comprising providing a secondplurality of cells, assembling the second plurality of cells into asecond cluster and disposing the second cluster on the plenum.
 22. Themethod of claim 21, wherein the second cluster is disposed within thehousing with the first cluster and plenum.
 23. The method of claim 21,further comprising: disposing a second insulation plate on the secondcluster; and disposing a second filter on the second insulation plate.24. The method of claim 19, wherein assembling the first plurality ofcells comprises connecting the first plurality of cells.
 25. The methodof claim 19, wherein assembling the first plurality of cells comprisestaping the first plurality of cells.
 26. A charger for charging abattery pack, the battery pack comprising a housing having top, bottomand side walls, a terminal tower disposed on the top wall, an air inletdisposed on at least one of the terminal tower and the top wall, and anair outlet for allowing air to exit from the housing, a plurality ofcells disposed in the housing, the charger comprising: a charger housingfor supporting the battery pack, the charger housing having a first ductopposite of the air inlet of the battery pack; charging circuitryprovided within the charger housing; and a fan disposed within thecharger housing for blowing air through the first duct and into thebattery pack via the air inlet, and for blowing air through a secondduct directing cooling air to the charging circuitry.
 27. The charger ofclaim 26, wherein the first duct and the air inlet of the battery packare axially aligned.
 28. The charger of claim 26, wherein the first ductand the air inlet of the battery pack are axially misaligned.
 29. Thecharger of claim 26, further comprising a chamber disposed between thefirst duct and the air inlet of the battery pack.
 30. A charger forcharging a battery pack, the battery pack comprising a housing havingtop, bottom and side walls, a terminal tower disposed on the top wall,an air inlet disposed on at least one of the terminal tower and the topwall, and an air outlet for allowing air to exit from the housing, aplurality of cells disposed in the housing, the charger comprising: acharger housing for supporting the battery pack, the charger housinghaving a first duct opposite of the air inlet of the battery pack andvents disposed near the air exiting from the battery pack housing; a fandisposed within the charger housing for blowing air through the firstduct and into the battery pack via the air inlet; wherein air exitingfrom the battery pack housing creates a low pressure region near thevents.
 31. The charger of claim 30, wherein the first duct and the airinlet of the battery pack are axially aligned.
 32. The charger of claim30, wherein the first duct and the air inlet of the battery pack areaxially misaligned.
 33. The charger of claim 30, further comprising achamber disposed between the first duct and the air inlet of the batterypack.
 34. A battery pack comprising: a housing having an air inlet forallowing air to enter the housing and an air outlet for allowing air toexit the housing; a first cell disposed within the housing; atemperature indicating device disposed within the housing for providingtemperature information, the temperature indicating device being exposedto air moving through the housing.
 35. The battery pack of claim 34,wherein the temperature indicating device is one of the group consistingof thermistors, thermostats, capacitors and resistors.
 36. A method forcontrolling a charger for charging a battery, wherein the chargercomprises a fan for cooling the battery, the method comprising:providing power to the fan so that it rotates at a first speed prior tobattery insertion.
 37. The method of claim 36, wherein the power isprovided when the charger is connected to a power supply source.
 38. Themethod of claim 36, wherein the power is provided when the charger isturned on.
 39. The method of claim 36, wherein the power is providedwhen a button disposed on the charger is activated.
 40. The method ofclaim 36, wherein the power is provided for a predetermined period oftime.
 41. The method of claim 36, further comprising providing power tothe fan so that it rotates at a second speed lower than the first speed.42. The method of claim 41, wherein the second speed is equal to zerorevolutions per minute.
 43. A method for controlling a charger forcharging a battery, wherein the charger comprises a fan for cooling thebattery, the method comprising: determining battery temperature;providing power to the fan so that it rotates at a first speed if thebattery temperature is above a predetermined temperature; and providingpower to the fan so that it rotates at a second speed lower than thefirst speed if the battery temperature is equal to or below apredetermined temperature.
 44. The method of claim 43, wherein thepredetermined temperature is about 20° C.
 45. The method of claim 43,wherein the second speed is equal to zero revolutions per minute.
 46. Amethod for controlling a charger for charging a battery, wherein thecharger comprises a fan for cooling the battery, the method comprising:providing power to the fan so that it rotates at a first speed;providing power to the fan so that it rotates at a second speed lowerthan the first speed determining battery temperature; and providingpower to the fan so that it rotates at a third speed.
 47. The method ofclaim 46, wherein the second speed is equal to zero revolutions perminute.
 48. The method of claim 46, wherein the third speed is selectedso as to maintain battery temperature at a predetermined temperature.49. The method of claim 48, wherein the predetermined temperature isabout 30° C.
 50. The method of claim 46, wherein the third speed isabout equal to the first speed.
 51. A method for cooling a batterydisposed on a charger, the method comprising: providing a fan in thecharger; providing an air inlet in the battery for allowing air to enterthe battery; providing an air outlet in the battery for allowing air toexit the battery; providing power to the fan to force air to enter thebattery through the air inlet, to exit the battery through the airoutlet and to enter the charger, in that order.